Can you play American PC games on an English PC

Yes. There are no differences in the alphabet, and only minor in grammar and spelling, so the game should be perfectly playable. Unlike television sets, video output is handled digitally, and is thus agnostic to differences in monitor technologies or framerates. Region lockout is also difficult to implement for a PC game, since Windows can use multiple language settings, even simultaneously, and to track it by IP address would render it unusable when you travel.